The Connecticut Longitudinal Study of Learning Disability (CLS) is a composite of an epidemiologic survey sample and a longitudinal cohort study of 445 children recruited initially in 1983 and prospectively followed from kindergarten through grade 11. This proposal seeks to follow this large and virtually intact sample (n=408) from grade 12, through the course of their transition to young adulthood (ages 18-23 years). The sample, the measures and the longitudinal framework allow us to address two central themes encompassing five specific aims: I. Prevalence, persistence and outcome - Specific Aims 1,2 and 3 II. Cognitive and neurobiologic mechanisms - Specific Aims 4 and 5. 1. Prevalence of Subgroups of LD and ADHD in a Sample Survey of Young Adults. 2. Nature and Determinants of Outcome in Childhood RD. 3. Nature and Determinants of Plateau Effects in Reading Over Time 4. Neurolinguistic and Biologic Mechanisms in Young Adults with a History of Childhood RD. 5. Definition of RD in Young Adults The Specific Aims outlined will provide the range and quality of data necessary to build a model of RD, one that is biologically-based, theoretically-driven and clinically meaningful. For the first time, clinicians and investigators alike, will have a clear and unbroken view of the full developmental course of RD. We will be able to look back at an entire population and determine particular antecedents predictive of specific outcomes, including reading achievement, educational attainment, occupational status and family and social adjustment as young adults. We will learn how specific childhood diagnoses, characteristics and experiences map onto a range of later adult outcomes. Finally, for the first time, we will be able to examine outcome in RD from a biological perspective by imaging the brain during reading. Knowledge of each of these components of RD: behavioral, cognitive and biological, will inform, and should significantly improve, clinical practice, including approaches to identification, intervention and prevention, while, at the same time, also providing the scientific foundation necessary for developing new hypotheses and strategies for studying reading and RD.